contentid (version 0.0.15)

history_url: List all content identifiers that have been seen at a given URL

Description

history_url is the complement of sources, in that it filters a table of content identifier : url : date entries by the url.

Usage

history_url(url, registries = default_registries(), ...)

Arguments

url

A URL for a data file

registries

list of registries at which to register the URL

...

additional arguments

Value

a data frame with all content identifiers that have been seen at a given URL. If the URL is version-stable, this should be a single identifier. Note that if multiple identifiers are listed, older content may no longer be available, though there is a chance it has been registered to a different url and can be resolved with sources.

Details

history_url() only applies to registries that contain mutable URLs, i.e. hash-archive and local registries which merely record the contents last seen at any URL. Such URLs may have the same or different content at a later date, or may fail to resolve. In contrast, archives such as DataONE or Zenodo that resolve identifiers to source URLs control both the registry and the content storage, and thus only report URLs where content is currently found. While Download URLs from archives may move and old URLs may fail, a download URL never has "history" of different content (e.g. different versions) served from the same access URL.

See Also

sources

Examples

# NOT RUN {

# }
# NOT RUN {
# }
# NOT RUN {
history_url(paste0("https://zenodo.org/api/files/5967f986-b599-4492-9a08",
"-94ce32323dc2/vostok.icecore.co2"), 
registries = "https://hash-archive.carlboettiger.info")
# }
# NOT RUN {
# }